CDI

We are honored to introduce the 4th International conference on Capacitive Deionization and Electrosorption, which will take place in Beijing, China, from May 20 to 23, 2019. The conference will be a good forum for CDI researchers to present the latest results, to draw inspiration and ideas, and to probe into the future development of CDI&E technologies. Twenty eight renowned scientists have confirmed as keynote or invited speaker. Moreover, more than 100 abstracts have already been submitted. Please visit our website for detailed information: http://cdi-e2019.csp.escience.cn/dct/page/70006.

You can still submit an abstract for an oral and/or poster presentation. The deadline for submission has been extended to November 30th, 2018.

Also, early registration is open from November 1st, 2018 to February 28th, 2019. More information related to the conference will be posted on the website soon.

The Department of Civil and Environmental Engineering of Penn State University (U.S.A.) seeks applicants for a full-time Post Doctoral position in CDI. The successful candidate will conduct research on development of novel types of desalination systems, such as battery electrode deionization, and membrane fouling. Applicants must have a PhD in Environmental Engineering or a related field. The candidate should have a good background in electrochemistry, and preferably experience in electrochemical desalination systems, as shown by publications on these topics or related topics in technical refereed journals.

Following the CDI conference recently held in the Republic of Korea, July 2017, twenty scientists active in the field of CDI worked on a joint position paper, putting forward the proposition that CDI defines a class of desalination technologies that share common operational principles and relevant metrics, thereby joining under one common term different CDI cell layouts and chemistries. Thus, according to the position paper, the class of CDI includes electrodes based on carbon materials, but as well electrodes with ion storage based on different chemistries such as using redox materials. The position paper can be downloaded via the link given below.

Last week's CDI-E's conference was a big success. 180 participants gathered for three full conference days in the heart of Seoul, Republic of South Korea. The conference, hosted by prof. Jeyong Yoon and his team of Seoul National University, proved invaluable in informing participants of all the latest developments in CDI technology, both from an academic and industrial perspective. The versatile program consisted of a tutorial session, plenary and keynote lectures, regular lectures and two poster sessions and gave food for thought to all attendants. The lively and amiable atmosphere gave the whole conference the right touch of feeling welcome in perhaps one of the most vibrant places in the world, the famous Gangnam district, a place that never sleeps.

The upcoming 3rd world conference on CDI&E "Capacitive Deionization, Electrosorption, and Electrodialysis" will be held July 3-6, 2017, in Seoul, Republic of Korea. Following earlier conferences in The Netherlands and Germany, we expect an attendance of over 200 delegates discussing all aspects of water treatment and desalination using electrochemical methods based on porous electrodes and/or ion-exchange membranes, from materials science and theoretical studies, to process engineering and commercial successes.

Two recent papers with authors from the US, The Netherlands, and Israel, convincingly show the relevance of chemical charge residing in the carbon electrodes ("immobile", or "complementary" charge) to enhance salt adsorption capacity (SAC) of CDI electrodes.

In the more theoretical paper of the two, published OPEN ACCESS in Colloids and Interfaces Science Communications, the theoretical framework is laid out which comprehensively describes the range of recently developed new CDI desalination modes such as inverted-CDI and (what the authors call) enhanced-CDI. Also the occurrence of "inversion peaks" which often develop during normal CDI operation are explained as due to developing chemical charge. In addition, a novel operational mode is described where due to the chemical charge, it becomes possible to enlarge the operating window of CDI and thus to enhance SAC further still. This operational mode of "extended voltage CDI" was not described before.

In the sequel paper, published in Water Research, both the enhanced-CDI regime and the extended-voltage CDI-regime are experimentally validated. In this paper the more advanced amphoteric Donnan model is used to describe the EDL-structure. This model quantitatively predicts the experimental observations of salt storage and charge. An interesting inconsistency is how the measured chemical charge (by titration) can be up to one order beyond the chemical charge derived from comparing the amph-D model to the data.

... and the field of Capacitive Deionization keeps on growing at an increasing speed ! While over 60 scientific publications are now written and published annually, citations to the CDI literature have grown from a number less than 100 per year before 2010, to about 2000 per year at the end of 2015, and this number continues to rise. Analysing citation data for the past 10 years, an exponential growth in citation rate is clearly observed, with a doubling of the citation rate every 18 months !

­Currently CDI devices consume significantly more energy than the theoretical thermodynamic minimum, and this is partly due to resistive power dissipation. To enhance the performance of CDI, identification of resistances in the CDI cell is important. Recently, two articles have been published on characterizing resistances in CDI and membrane-CDI (MCDI).

Researchers from Stanford University (US) published an article in Environmental Science and Technology. They characterize electrical resistances in a CDI system, present an equivalent circuit model and propose measurable figures of merit to describe cell resistance. They also found that contact resistance between current collectors and porous electrodes is the major contributor to cell resistance in nearly all published CDI cells. Contact resistance can be reduced by either introducing contact pressure between current collectors and electrodes or using pore-filling adhesive to create a point contact configuration. They emphasize here that energy consumption of the CDI process is the unrecoverable dissipated energy during an operation cycle, which should not include stored capacitive energy.

Researchers from Wageningen University and Wetsus (The Netherlands) published an article in Water Research. They outline a method to identify electronic and ionic resistances. They illustrate their method by calculating the resistances in an MCDI cell, for which they derived a full-scale model. This model is validated against experimental data and used to calculate the ionic resistances across the MCDI cell. Furthermore, they present a way to measure ionic and electronic resistances in a CDI cell, as well as establish the spacer channel thickness and porosity after assembly of the MCDI cell. Based on their findings, they show that, for MCDI, the carbon electrode thickness can be increased without significantly increasing energy consumption, which has the advantage that desalination time can be lengthened significantly.

October 25-29, 2015, the International Conference on CDI&Electrosorption was organized by the Institute of New Materials (INM) in Saarbrücken, Germany. In a beautiful location on the pittoresque campus of Saarland University, 120 attendees from all around the globe participated in lectures, a CDI-tutorial, and a poster session, with lively discussions during coffee breaks and lunches. An inspiring and diverse program was organized by the conference chair prof. Volker Presser (INM) and co-chair prof. Matthew Suss (Technion, Israel). Many new contacts were made during the opening mixer, the memorable excursion to an old steel and coal factory, and during the delicious gala dinner. We look back at a wonderful and very successful CDI&Electrosorption conference.

In a collaboration involving scientists from five different countries in two continents, members of the CDI&E working group used the past year to come with a Perspective-paper on capacitive ionization and electrosorption. Published on invitation in the high-impact journal Energy&Environmental Science (IF=25) as a prestigious Perspective-contribution, the paper is expected to generate attention inside and outside the CDI-field. To help quick dissemination of its content, the authors have chosen for the OPEN ACCESS-format.

As corresponding authors Prof.Dr. Mathew Suss and Prof.Dr. Volker Presser explain: "The idea for this perspective was conceived of during the last CDI-conference in Leeuwarden, the Netherlands, and our aim is that it serves the growing CDI-community in outlining current trends in CDI developments, in standardizing metrics, and to help by identifying 'white areas' in CDI, both experimentally and theoretically. It was a most exhilarating task to work together with so many different authors on different continents to see this paper growing over the year. Many discussions helped us to focus on the most important elements and to converge on the key trends and best metrics for CDI performance. We have done our very best to put together a paper that helps to catalyze scientific and industrial developments in the CDI&E-field."